If everyone was aloud to throw flashes when they pleased than it would create numerous opportunities for terrorists to rebel. Its all really about the judgment of said player and the admin in the server. Usually a warning shot will suffice for the situation, but often times a smart terrorist will throw the flash at a critical moment in a area of the map that opens a key opportunity for them to rebel. Flashes cannot be used for fun, they are always used with the intention of harming the counter terrorist. Smokes are a different story and really has to do with the location where the smoke was deployed.
